This invention relates generally to blades that may be useful as wind turbine rotor blades and to rotors and wind turbines utilizing such blades.
Some known wind turbine rotor blades may generate considerable noise, particularly at higher rotor speeds, which may bother people and/or entities, for example residential communities, located near the wind turbine. As a consequence, authorities with responsibility for granting permission for setting up wind turbines may refuse permission because of the noise levels. For example, in some parts of the world, issuance of permits for wind turbines is based on the environmental noise impact affected or potentially affected by the wind turbine.
One example of noise emitted by known wind turbine rotor blades is noise emitted from trailing edges of the blades because of interaction between boundary layer air and the trailing edge. Generally, greater trailing edge thicknesses generate higher noise levels. However, manufacturing and transporting blades with a reduced trailing edge thickness may be difficult, for example, without damaging the trailing edge. Accordingly, some known blades include a separate trailing edge piece that covers and reduces a thickness of the trailing edge. The separate trailing edge piece can be mounted on the blade after transportation of the blade to a wind turbine. However, some known separate trailing edge pieces may not mount flush with an outer surface of the blade. Accordingly, although the separate trailing edge piece may reduce a thickness of the blade, a seam between the separate trailing edge piece and the outer surface may increase noise emitted because of interaction of boundary layer air with the seam. Some known rotor blades use custom trailing edge pieces designed to fit generally flush to a specific blade shape. However, such custom trailing edge pieces may only fit the specific blade shape they are designed for and therefore may increase an overall cost of a group of wind turbines having differently shaped rotor blades.